definitions Flashcards
Transverse waves
waves that are perpendicular to the direction of the wave motion
speed of light travelled in a vacuum
3x10 ^8 ms-1
electromagnetic spectrum
visible light waves are electromagnetic waves
red light 760nm
violet light 390nm
diverge
as light travels outwards from a source the wavefronts flatten and diverge
negative value
converge
as light travels towards a focal point the wavefronts become more curved and light converges
positive value
vergence
the higher the wavefront value the more curved the wavefronts are
as the mergence value drops the wavefronts become flatter
light from infinity
will have 0 vergence the light rays will be parallel
prisms
will change the direction of the incident light will travel after refraction
the light is deviated from its original course
functions of prisms
may be used to obtain optical centration
used to maintain binocular vision
corrects or relieves imbalance in the muscles of the eye
pinhole camera
consists of a light-tight box of adjustable length
pinhole camera properties
image is inverted
image is well defined over long range of distances
can increase the size of the image by increasing length of the box but reduces brightness
entirely free of distortion
increasing pinhole size will increase brightness but less distinct image
pinhole in use
pinhole discs are used in trial frames in practice
pinhole glasses offer a cheap way of improving visual performance
refraction at a plane surface
when light travels into a more optically-dense medium it slows down and the waves bunch together
snells law
n1.sini1=n2.sini2
illuminance
the measure of light falling on a unit area of a surface
